I have been riding thrusters for 20 years and still do. But when the surf is small, and I mean small I get on my quad. Now my quad is not like your USA quads, my fins are up the board and are relatively small. The board also has absolutely no rocker, is 5"8 and 24" wide x 2"7/8, its a boat.
When I ride it, like all Aussie quads (fins up the board) it surfs very flat and wont go full tilt on its rail, if you push the board through a cutty it stays relatively flat compared to my thruster, and wont drive around anywhere near as deep as my thruster (without doing a 2 or 3 stage cutty). Which in small waves is perfect, because there is not enough face to drive a full rail roundhouse on. You can flick the thing around very easily, might look alright to watch but its not a full rail roundhouse. Badens surfing next to Simon's makes this very obvious. Just look at the spray line coming of the bottom of the board, if its broken then its been done in stages, if its clean all the way its a one stage turn. Also the four allows you to go flat between linking turns (awesome in small surf-faster and less drag), where as the thruster (look at simon) is complete rail-link-to rail turn.
I would tend to disagree with Erics quote, depending on the quads fin placement "The tri turns much easier on its fins whereas the quad turns better on its rails, with speed needed for the quad." My thrusters need speed or size to work but my four just needs a tweak of my arse cheek to flick it around. I do agree with the fin point, buts its a drive thing on a thruster not a turn.
Thrusters=drive rail to rail
Quads=turn flat turn
again depending on your fin placement
If I surf my quad in any waves of consequence, to go vertical I have to do a 2 stage turn to try and get up there, where as the thruster will draw a clean, sharper 1 stage turn and go straight at the lip. When you hit the lip on the quad, tweak that arse cheek and your pointing straight back down, on the thruster you have to drive back around (lots more effort needed on the thruster and it feels better)
I am a firm believer of different boards for different waves, in that footage of Simon and Baden, Simon's choice of equipment is what makes it look easier and his moves finished. I like to be able to ride every board I get to its full potential (well thats the plan) and realise in what conditions it will best perform, only to enhance my enjoyment of riding a kneelo, plus you learn more evertime you ride something different.
Andrew-I think you mixed bruces quote up....Baden actually does have a twin brother called Andrew who ripped it up on a four finner aswell, andrew won a australian title then retired from competition
Hope my mumbling made some sense.
You had to post that photo of Parkes throwing gobs of spray on his quad. Back to restless nights.
. So, does that mean that the closer the fins are to the tail, the easier it is to get on the rail?